Polymers of napthalene tetracarboxylic diimide dimers

ABSTRACT

Polymers of naphthalene tetracarboxylic diimide dimmers are provided. The polymers are of the Formula I 
                         
wherein the A units are selected from
 
                         
and Formula IX
 
                         
The polymers are suitable for use in the active layer of an imaging member and exhibit properties of both a binder and an electron-transporting material.

BACKGROUND

Illustrated herein in various exemplary embodiments are polymermaterials containing naphthalene tetracarboxylic diimide (NTDI) dimers.The polymer materials containing NTDI dimers are capable of functioningas both a binder and an electron-transporting material in anelectrophotographic element. Also illustrated herein are.electrophotographic or photoconductor elements that include such polymermaterials. These materials find particular application in conjunctionwith xerographic and electrostatographic printing processes, and will bedescribed with particular reference thereto. It is to be appreciated,however, that the present disclosure and exemplary embodiments are alsoamenable to other applications.

Many electrophotographic elements currently in use are designed to beinitially charged with a negative polarity. Such elements contain amaterial that facilitates the migration of positive holes toward thenegatively charged surface in imagewise exposed areas in order to causeimagewise discharge. Such a material is often referred to as ahole-transport agent. In electrophotographic elements of that type, apositively charged toner material is usually then used to develop theremaining imagewise undischarged areas of negative polarity potential,i.e., the latent image, into a toner image. Because of the wide use ofnegatively charging elements, considerable numbers and types ofpositively charging toners have been fashioned and are available for usein electrophotographic developers.

However, for some applications of electrophotography it is moredesirable to be able to develop the surface areas of the element thathave been imagewise exposed to actinic radiation, rather than those thatremain imagewise unexposed. For example, in laser printing ofalphanumeric characters it is more desirable to be able to expose therelatively small percentage of surface area that will actually bedeveloped to form visible alphanumeric toner images, rather than wasteenergy exposing the relatively large percentage of surface area thatwill constitute undeveloped background portions of the final image. Inorder to accomplish this while still employing widely available highquality positively charging toners, it is necessary to use anelectrophotographic element that is designed to be positively charged.Positive charging toner can then be used to develop the exposed surfaceareas, which will have, after exposure and discharge, relativelynegative electrostatic potential compared to the unexposed areas, wherethe initial positive potential will remain. An electrophotographicelement designed to be initially positively charged may contain anadequate electron-transport agent, that is, a material which facilitatesthe migration of photogenerated electrons toward the positively chargedinsulative element surface.

Electrophotographic elements include both those commonly referred to assingle layer, or single-active-layer, elements and those commonlyreferred to as multiactive, multilayer, or multi-active-layer elements.

Single-active-layer elements are so named because they contain only onelayer that is active both to generate and to transport charges inresponse to exposure to actinic radiation. Such elements typicallycomprise at least an electrically conductive layer in electrical contactwith an active layer. In single-active-layer elements, the active layercontains a charge-generation material to generate electron/hole pairs inresponse to actinic radiation and an electron-transport and/orhole-transport agent, which comprises one or more of chemical compoundscapable of accepting electrons and/or holes generated by thecharge-generation material and transporting them through the layer toeffect discharge of the initially uniform electrostatic potential. Theactive layer is electrically insulative except when exposed to actinicradiation, and it sometimes contains an electrically insulativepolymeric film-forming binder, which may itself be the charge-generatingmaterial, or it may be an additional material that is notcharge-generating. In either case, the transport agent(s) is (are)dissolved or dispersed as uniformly as possible in the layer.

Multiactive elements are so named because they contain at least twoactive layers, at least one charge generation layer (CGL) which iscapable of generating charges, i.e., electron/hole pairs, in response toexposure to actinic radiation, and at least one charge transport layer(CTL) which is capable of accepting and transporting charges generatedby the charge-generation layer. Such elements typically comprise atleast an electrically conductive layer, a CGL, and a CTL. Either the CGLor the CTL is in electrical contact with both the electricallyconductive layer and the remaining CTL or CGL. The CGL contains at leasta charge-generation material; the CTL contains at least acharge-transport agent; and either or both layers can contain anelectrically insulative film-forming polymeric binder.

In multiactive, positively charged photoconductor elements of the typeemploying at least a CGL and a CTL, the CTL may be the uppermost layerof the element to protect the more mechanically sensitive CGL from wear.Known electron-transport agents may suffer from one or more problemsupon repeated use, such as high dark decay, insufficient electroniccharge transport activity, a gradually increasing residual potential orthe like. Certain electron-transport agents, such as trinitrofluorenone(TNF), which do exhibit a useful level of sensitivity, suffer from thefurther disadvantage that they are now suspected to be carcinogens.

As mentioned, in both single-active-layer elements and multiactive layerelements, the transporting materials, such as electron-transportmaterials and hole transport materials, are typically dispersed in apolymeric binder. In particular, the transporting materials may bedispersed as a solid state solution in a polymeric binder material.Generally, device performance may be increased by increasing theconcentration of the respective transport materials in a given activelayer element. The concentration of the transport materials, however, islimited by the solubility of the transport materials in the binder. Asingle-layer photoreceptor, for example, typically comprises about 48 wt% of a polymeric binder, 30 wt % of a hole-transporting molecule, 20 wt% of an electron-transporting molecule, and 2 wt % of a chargegenerating material, such as a charge generating pigment. This, however,appears to be the upper limit for the concentrations of the respectivecomponents to form a solid state solution without crystallization of thetransport molecules and/or loss of mechanical integrity of the device.

Thus, there is a need to provide materials that will allow for anincrease in the concentrations of the transport materials in an activelayer of a photoreceptor and still form a solid state solution. One wayto achieve such a result would be to provide materials that have dualfunctionalities, i.e., function as both a binder and a transportmaterial. U.S. Pat. Nos. 5,814,426; 5,874,192; and 5,882,814, the entiredisclosures of which are incorporated herein by reference, disclose holetransport materials that also function as binder materials. U.S. Pat.No. 5,266,429 is directed to a polyesterimide that includes a dioxycomponent and a dicarbonyl component, one of which contains atetracarbonyldiimide group. The polyesterimide in U.S. Pat. No.5,266,429 may be used as a binder layer or may be the sole material in acharge transport layer.

As between electron-transporting materials and hole-transportingmaterials, hole-transporting materials are generally more compatiblewith polymeric binder materials. That is, hole-transporting materialswill form a solid state solution over a wider concentration range thanwill electron-transport materials. Therefore it is desirable to providea hybrid material that is capable of function as a binder material andan electron-transporting material.

BRIEF DESCRIPTION

In one aspect, provided herein in one embodiment is an A compound of the

wherein:the A unit is selected from the group consisting of:

-   -   R₁ is independently selected from the group consisting of a        hetero atom containing group and a hydrocarbon group that is        optionally substituted at least once with a hetero atom moiety;    -   R₂ and R₃ independently selected from the group consisting of a        hydrocarbon group or a substituted hydrogen group;    -   R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ an are independently        selected from the group consisting of a nitrogen contain group,        a sulfur containing group, a hydroxyl group, a silicon        containing group, hydrogen, a halogen, a hetero atom containing        group, a hydrocarbon group and a substituted hydrocarbon group;    -   R₁₃ is selected from the group consisting of

-   -   R₁₄ is selected from the group consisting of a hydrocarbon group        and a substituted hydrocarbon; and    -   R₁₅ is selected from the group consisting of

wherein Z is an electron withdrawing group.

In another aspect, the present disclosure provides:

an A compound of Formula IX

wherein R₁ is independently selected from the group consisting of ahetero atom containing group, a hydrocarbon containing group, and ahydrocarbon group substituted at least once with a hetero atom moiety;

-   -   R₁₂ is independently selected from the group consisting of a        nitrogen contain group, a sulfur containing group, a hydroxyl        group, a silicon containing group, hydrogen, a halogen, a hetero        atom containing group, a hydrocarbon group and a substituted        hydrocarbon group;    -   R₁₆ is selected from:

andwherein R₁₇ is independently selected from the group consisting of anitrogen contain group, a sulfur containing group, a hydroxyl group, asilicon containing group, hydrogen, a halogen, a hetero atom containinggroup, a hydrocarbon group and a substituted hydrocarbon group;and

-   -   R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently selected        from the group consisting of a nitrogen containing group, a        sulfur containing group, a hydroxyl group, a hydrocarbon group,        and a hydrocarbon group that is substituted at least once with a        hetero atom moiety.

In still another aspect, the present disclosure provides:

-   -   a photoconductive imaging member comprising    -   a substrate, and    -   a single active layer formed over the substrate, the single        active layer comprising a mixture of a photogenerating        component, a hold transport material, and a polymer material        selected from a polymer of the Formula I

and a polymer of the Formula IX

wherein A is selected from the group consisting of

-   -   R₁ is independently selected from the group consisting of a        hetero atom, containing group, a hydrocarbon group, and a        hydrocarbon group substituted at least once with a hetero atom        moiety;    -   R₂ and R₃ are independently selected from the group consisting        of a hydrocarbon group or a substituted hydrocarbon group;    -   R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently selected        from the group consisting of a nitrogen containing group, a        sulfur containing group, a hydroxyl group, a silicon containing        group, hydrogen, a halogen, a hetero atom containing group, a        hydrocarbon group, and a hydrocarbon group substituted at least        once with a hetero atom moiety;    -   R₁₂ is independently selected from the group consisting of a        nitrogen contain group, a sulfur containing group, a hydroxyl        group, a silicon containing group, hydrogen, a halogen, a hetero        atom containing group, a hydrocarbon group and a substituted        hydrocarbon group;    -   R₁₃ is selected from the group consisting of

-   -   R₁₄ is selected from the group consisting of a hydrocarbon group        and a substituted hydrocarbon;    -   R₁₅ is selected from the group consisting of

wherein Z is an electron withdrawing group;

-   -   R₁₆ is selected from the group consisting of

andWherein R₁₇ is independently selected from the group consisting of anitrogen contain group, a sulfur containing group, a hydroxyl group, asilicon containing group, hydrogen, a halogen, a hetero atom containinggroup, a hydrocarbon group and a substituted hydrocarbon group;andn is a fraction between 0 and 1.

In yet another aspect, the present disclosure provides a photoimagingmember comprising a substrate; a charge generating layer; and a chargetransport layer, wherein said charge transport layer comprises a polymercomposition comprising a naphthalene tetracarboxylic diimide dimercomponent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a first illustrative synthesis route for preparingdihydroxy naphthalene tetracarboxylic diimide dimers;

FIG. 2 depicts a second illustrative synthesis route for preparingdihydroxy naphthalene tetracarboxylic diimide dimers;

FIG. 3 depicts a first illustrative synthesis route for formingpolycarbonates;

FIG. 4 depicts a second illustrative synthesis route for formingpolycarbonates;

FIG. 5 depicts a third illustrative synthesis route for formingpolycarbonates;

FIG. 6 depicts an illustrative synthesis route for forming polyesters;

FIG. 7 depicts an illustrative synthesis route for formingpolyarylyethers; and

FIG. 8 depicts an illustrative synthesis route for forming a hybridbinder/electron-transporting polyimide containing a naphthalenetetracarboxylic diimide dimer.

Unless otherwise noted, the same reference numeral in different Figuresor Formulas described or illustrated herein refers to the same orsimilar feature.

DETAILED DESCRIPTION

Illustrated herein, in various exemplary embodiments, are polymermaterials that are capable of functioning as a polymer binder materialand an electron transporting material in an active layer of aphotoconductor. In particular, the polymer materials comprisenaphthalene tetracarboxylic diimide dimers. In embodiments, thepolymeric materials may be represented as a compound of the Formula I:

wherein n=is a fraction between 0 and 1.

Compounds of Formula I are generally polymer materials that include abase polymer unit or component, such as repeating unit A in Formula I,and a naphthalene tetracarboxylic diimide dimer component. Inembodiments, compounds of the Formula I are polycarbonates, polyesters,or polyarylethers having a naphthalene tetracarboxylic diimide dimercomponent. Component A is referred to herein as the binder or resincomponent.

The naphthalene tetracarboxylic diimide dimer component comes fromnaphthalene tetracarboxylic diimide dimers. Naphthalene tetracarboxylicdiimide dimers are described in co-pending application Ser. No.10/197,933, published as U.S. Patent Application Publication No.2004/0013959, the entire disclosure of which is incorporated herein byreference. An example of naphthalene tetracarboxylic diimide dimerinclude the dihydroxyl form as represented by the compound of FormulaII:

wherein n=is a fraction between 0 and 1.The substituent R₁ is independently selected from the group consistingof a hetero atom containing group and a hydrocarbon group that isoptionally substituted at least once with a hetero atom moiety. As usedherein, the phrase hetero atom containing group indicates that there ispresent at least one other type of atom other than carbon and hydrogenwithin the group and that the hetero atom or hetero atoms are part ofthe main structural chain of the group, such as, for example,3-oxa-pentan-1,5-diyl. As used herein, the phrase hetero atom moietyindicates that there is present at least one other type of atom otherthan carbon and hydrogen within the group and that the hetero atommoiety is not part of the main structural chain of the group, such as,for example 2-hydroxy-propan-1,3-diyl. The term hydrocarbon refers toany moiety composed of carbon atoms and hydrogen atoms. The hydrocarbonmay optionally be a substituted hydrocarbon where one or more of thehydrogen atoms are replaced with another substituent. Furthermore, theterm hydrocarbon includes for instance acyclic hydrocarbons, alicyclichydrocarbons, aromatic hydrocarbons and the like which may be optionallysubstituted.

Examples of moeties suitable as the hetero atom containing group (forR₁) include, but are not limited to, (a) an alkoxy group having fromabout 3 to about 30 atoms, and in embodiments from about 3 to about 6atoms such as, for example, 3-oxa-pentan-1,5-diyl, an aldehyde group,and a ketone group; (b) a heterocyclic system having from about 11 toabout 30 atoms such as, for example, N-phenylcarbazol-3,5-diyl; and (c)an alkoxyaryl having from about 7 to about 30 atoms such as, forexample, 2-methoxybenzen-1,4-diyl and 2-ethoxybenzen-1,4-diyl.

Examples of the hydrocarbon group (for R₁) include, but are not limitedto, (a) a straight chain alkyl group having from about 1 to about 30carbon atoms, and in embodiments from 1 to about 6 carbon atoms, suchas, for example, ethan-1,2-diyl, butan-1,4-diyl, hexan-1,6-diyl, and thelike; (b) a branched alkyl group having from about 3 to about 30 carbonatoms, and in embodiments from about 3 to about 6 carbon atoms such as,for example, 2-methylpentan-1,5-diyl and 2,2-dimethylpropan-1,3-diyl;(c) a cycloalkyl group having from about 3 to about 20 carbon atoms, andin embodiments from 4 to about 6 carbon atoms such as, for example,cyclopentan-1,3-diyl and cyclohexan-1,4-diyl; (d) a monocyclic aromaticgroup such as, for example, phenyl like benzen-1,2-diyl, benzen-1,3-diyland benzen-1,4-diyl; (e) a polycyclic aromatic group having from about11 to about 30 carbon atoms such as, for example, naphthyl (e.g.,naphthalen-1,5-diyl and naphthalene-2,7-diyl) and anthracen-9,10-diyl;(f an alkylaryl group having from about 7 to about 30 carbon atoms suchas, for example, p-xylen-α,α-diyl; and (g) an arylalkyl group havingfrom about 7 to about 30 carbon atoms such as, for example,2,5-diisopropylbenzen-1,4-diyl.

Any of the hydrocarbon groups can be optionally substituted one, two, ormore times with the same or a different substituting moiety including,but not limited to, (a) a nitrogen containing group such as, forexample, amino and nitro; (b) a sulfur containing group such as, forexample, thiol, sulfoxide, sulfate, chlorosulfate and the like; (c) ahydroxyl group; (d) a silicon containing group such as, for example, atrisubstituted silane where the substituent is a hydrocarbon; (e) ahalogen such as, for example, bromine, chlorine, fluorine, and iodine;and (e a hetero atom moiety, having about 3 to about 15 atoms, andincluding an element selected from the group consisting of, for example,nitrogen, sulfur, silicon, and oxygen, such as, for example,thiophen-2-yl, thiophen-3-yl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl,furan-2-yl, furan-3-yl and the like. Non-limiting examples of suitablesubstituted hydrocarbon groups include, but are not limited to, thefollowing: 3-hydroxyhexan-1,6-diyl; 2-methylbenzen-1,4-diyl; and2,5-dimethylbenzen-1,4-diyl.

For reasons further described herein, with respect to the naphthalenetetracarboxylic diimide dimers used in the present disclosure, R₂ and R₃are independently selected from the group consisting of substitutedhydrocarbon groups. In particular, R₂ and R₃ are hydroxyl substitutedhydrocarbon groups such as shown in Formula II. Examples of suitablehydroxyl substituted hydrocarbon groups include, but are not limited to,straight chain alkyl groups having from about 1 to about 30 carbonatoms, branched alkyl groups having from about 3 to about 30 carbonatoms, cycloalkyl groups having from about 3 to about 20 carbon atoms,monocyclic aromatic groups having such as, for example, phenyl andbenzenyl, polycyclic aromatic groups having from about 11 to about 30carbon atoms, alkylaryl groups having from about 7 to about 30 carbonatoms, and arylalkyl groups having from about 7 to about 30 carbonatoms. In embodiments, R₂ and R₃ may be different hydrocarbons groups.In other embodiments, R₂ and R₃ are the same hydrocarbon group.

R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ may be independently selected fromthe group consisting of a nitrogen containing group, a sulfur containinggroup, a hydroxyl group, a silicon containing group, hydrogen, a halogen(e.g., bromine, chlorine, fluorine, and iodine), a hetero atomcontaining group and a hydrocarbon group that is optionally substitutedat least once with a hetero atom moiety.

Examples of suitable hetero atom containing group (for R₄ through R₁₁)include but are not limited to, (a) an alkoxy group having about 3 toabout 30 atoms, and, in embodiments, from about 3 to about 6 atoms suchas, for example, 3-oxa-butan-1-yl, 4-methyl-3-oxapent-1-yl, an aldehydegroup, and a ketone group; (b) a heterocyclic system having, forexample, 11 to about 30 atoms such as N-phenylcarbazol-3-yl,thiophen-2-yl, thiophen-3-yl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl,furan-2-yl, furan-3-yl and the like; (c) an alkoxyaryl having about 7 toabout 30 atoms such as, for example, 4-methoxybenzen-1-yl and4-ethoxybenzen-1-yl; and (d) an arylalkoxy having about 7 to about 30atoms such as, for example, 3-oxa-3-phenylpropan-1-yl; and (e) anaryloxy having about 7 to about 30 atoms such as, for example,3-methylphenoxy, 4-nonylphenoxy, 1-naphthoxy and 2-naphthoxy.

Examples of compounds suitable as the hydrocarbon group (for R₄ throughR₁₁) include, but are not limited to, (a) a straight chain alkyl grouphaving 1 to about 30 carbon atoms, and in embodiments 1 to about 4carbon atoms, such as, for example, ethanyl and butanyl; (b) a branchedalkyl group having about 3 to about 30 carbon atoms, and in embodimentsabout 3 to about 4 carbon atoms such as, for example,1-methylpropan-1-yl, 1-methylethan-1-yl and 1-methylmethan-1-yl; (c) acycloalkyl group having about 3 to about 20 carbon atoms, and inembodiments 4 to about 6 carbon atoms such as, for example,cyclopentanyl and cyclohexanyl; (d) a monocyclic aromatic group such as,for example, phenyl like benzenyl; (e) a polycyclic aromatic grouphaving about 11 to about 30 carbon atoms such as, for example, naphthyl(e.g., naphthalene-1-yl and naphthalene-2-yl) and anthracen-9-yl; (f) analkylaryl group having about 7 to about 30 carbon atoms such astoluen-α-yl; and (g) an arylalkyl group having about 7 to about 30carbon atoms such as 4-ethylbenzen-1-yl and 4-sec-butylbenzen-1-yl.

Examples of suitable moieties substitutions on the hydrocarbon group(any of the hydrocarbon groups can be optionally substituted one, two,or more times with the same or different substituting moiety) and ofsubstituents for R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ include, but arenot limited to, (a) a nitrogen containing group such as, for example,amino and nitro; (b) a sulfur containing group such as, for example,thiol, sulfoxide, sulfate, chlorosulfate; (c) a hydroxyl group; (d) asilicon containing group such as, for example, a trisubstituted silanewhere the substituent is a hydrocarbon; (e) a halogen such as, forexample, bromine, chlorine, fluorine, and iodine; and (f) a hetero atommoiety, having, for example, about 3 to about 15 atoms, and including anelement selected, for instance, from the group consisting of nitrogen,sulfur, silicon, and oxygen, such as, for example, thiophen-2-yl,thiophen-3-yl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, furan-2-yl,furan-3-yl and the like. Examples of suitable substituted hydrocarbongroups include, but are not limited to, for instance:2-hydroxyethan-1-yl, 3-hydroxypropan-1-yl, 2-methylbenzen-1-yl,2,6-diisopropylbenzen-1-yl, 2, 5-dimethylbenzen-1-yl,4-methylnapthalen-1-yl, and 5-methylnapthalen-2-yl.

As previously described herein, in embodiments, the base polymercomponent, i.e., component A in Formula I, may be a polycarbonate, apolyester, or a polyarylether. Polycarbonate, polyester, andpolyarylether components are represented as follows in Formulas III-V,respectively:

In embodiments where the compound of Formula I is a polycarbonate, the Acomponent is a repeating unit as shown in Formula III, and the compoundhas a structure as shown in Formula VI:

wherein n is a fraction between 0 and 1. Non-limiting examples of groupssuitable as the R13 group include:

In embodiments where the compound of Formula I is a polyester, the Acomponent is a repeating unit as shown in Formula IV, and the compoundhas a structure as shown in Formula VII:

wherein n is a fraction between 0 and 1. R₁₄ may be chosen from thegroup of hydrocarbon and substituted hydrocarbon. Examples of suitablehydrocarbon groups include, but are not limited to, straight chain alkylgroups having from about 1 to about 30 carbon atoms, branched alkylgroups having from about 3 to about 30 carbon atoms, cycloalkyl groupshaving from about 3 to about 20 carbon atoms, monocyclic aromatic groupssuch as, for example, phenyl and benzenyl, polycyclic aromatic groupshaving from about 11 to about 30 carbon atoms, alkylaryl groups havingfrom about 7 to about 30 carbon atoms, and arylalkyl groups having fromabout 7 to about 30 carbon atoms. Where R₁₄ is a substitutedhydrocarbon, suitable substituting moieties include, but are not limitedto, a nitrogen containing group, a sulfur containing group, a hydroxylgroup, a silicon containing group, a halogen, or a hetero atom moietyhaving, for example, about 3 to about 15 carbon atoms and including anelement selected from the group consisting of nitrogen, sulfur, silicon,and oxygen.

In other embodiments, compounds of the Formula I are a polyarylether. Insuch compounds, the repeating unit A is of a type as shown in Formula V,and the compound has a structure of Formula VIII:

wherein n is a fraction between 0 and 1. In embodiments, R₁₅ is selectedfrom moieties including, for example:

In embodiments, Z is an electron withdrawing group. Additionally, R₁₃may be those moieties previously described herein as suitable for R₁₃with respect to the polycarbonate polymers.

Polymer materials of the Formula I are generally formed by the reactionof a dihydroxy naphthalene tetracarboxylic diimide dimer and apolycarbonate, polyester, or polyarylether component. FIGS. 1 and 2depict illustrative synthesis routes to prepare the dihydroxynaphthalene tetracarboxylic diimide dimer component. In FIGS. 1 and 2,R₂ and R₃ are shown as “R₂(R₃)” in the final compound and the reagentsbecause the depicted synthesis pathways are primarily for the situationwhere R₂ and R₃ are symmetrical, i.e., they are the same. However, thepresent disclosure also encompasses the preparation of unsymmetricalcompounds where R₂ and R₃ are different from each other.

The synthesis of symmetrical dihydroxy naphthalene tetracarboxylicdiimide dimers (where R₂ and R₃ are the same) can be accomplished by amulti-step synthesis starting from 1,4,5,8-naphthalenetetracarboxylicacid or dianhydride by either of two routes. In the first route, asdepicted in FIG. 1, a 1,4,5,8-naphthalene tetracarboxylic diimide dimeris synthesized as follows: 1,4,5,8-naphthalene tetracarboxylic acid ordianhydride is dissolved in aqueous alkali which is then treatedsequentially with concentrated phosphoric acid, an aliphatic oralicyclic hydroxyl substituted monofunctional amine and heated to 90° C.for a period of time. Any insoluble material is filtered after whichconcentrated phosphoric acid is added to precipitate the product whichcan be collected, further purified and dried to remove residual water.Reaction of this material with a difunctional amino compound (such as1,4-diaminobutane or 2,2-dimethyl-1,3-propane diamine) at elevatedtemperature in a suitable solvent (such as N,N-dimethylformamide,N,N-dimethylacetamide, quinoline, m-cresol, acetic acid and the like andmixtures thereof) yields a dihydroxy 1,4,5,8-naphthalene tetracarboxylicdiimide dimer on isolation and purification.

In the second route, as depicted in FIG. 2, a 1,4,5,8-naphthalenetetracarboxylic diimide dimer is synthesized as follows:1,4,5,8-naphthalene tetracarboxylic acid or dianhydride is dissolved inaqueous alkali which is then treated sequentially with concentratedphosphoric acid, a difunctional amine (such as 1,4-diaminobutane or2,2-dimethyl-1,3-propane diamine) and heated to 90° C. for a period oftime. Any insoluble material is filtered after which concentratedphosphoric acid is added to precipitate the product which can becollected, further purified and dried to remove residual water. Reactionof this material with an aliphatic or alicyclic hydroxyl substitutedmonofunctional amino compound (such as 4-aminobutane or 4-aminopentane)at elevated temperature in a suitable solvent (such asN,N-dimethylformamide, N,N-dimethylacetamide, quinoline, m-cresol,acetic acid and the like and mixtures thereof) yields the dihydroxy1,4,5,8-naphthalene tetracarboxylic diimide dimer on isolation andpurification.

If it is so desired to have a 1,4,5,8-naphthalene tetracarboxylicdiimide dimer where R₂ is not equal to R₃ such a dimer could besynthesized as follows: A compound 2 (see FIG. 2) is dissolved inaqueous alkali which is then treated sequentially with concentratedphosphoric acid, a difunctional amine (such as 1,4-diaminobutane or2,2-dimethyl-1,3-propane diamine) and heated to 90° C. for a period oftime. Any insoluble material is filtered after which concentratedphosphoric acid is added to precipitate the product which can becollected, further purified and dried to remove residual water. Reactionof this material with an aliphatic or alicyclic hydroxyl substitutedmonofunctional amino compound (such as 4-aminobutane or 4-aminopentane)at elevated temperature in a suitable solvent (such asN,N-dimethylformamide, N,N-dimethylacetamide, quinoline, m-cresol,acetic acid and the like and mixtures thereof) yields a dihydroxy1,4,5,8-naphthalene tetracarboxylic diimide dimer on isolation andpurification.

Dihydroxy naphthalene tetracarboxylic diimide dimers can be preparedaccording to the general schemes shown in FIGS. 1-2. In embodiments, thedihydroxy dimers are prepared by the route depicted in FIG. 2. In thisroute, the intermediate compound 2 can be prepared at higher puritylevels than a compound 1.

It will be apparent to those skilled in the art that the proceduresdescribed herein will be generally insensitive to the choice of R₄, R₅,R₆, R₇, R₈, R₉, R₁₀ and R₁₁. It will also be apparent that theintroduction of R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ and R₁₁ shouldpreferentially be performed before undertaking the synthetic sequencedescribed herein. That is, the starting materials may be changed from1,4,5,8-naphthalene tetracarboxylic diacid (or dianhydride) to amaterial that already contains the desired substitution pattern. Forthose compounds not commercially available their synthesis would berequired before undertaking the synthetic procedure described in thisdisclosure. The synthesis of naphthalene tetracarboxylic acids is aknown process and is illustrated in the following figure (see W. Herbstand K. Hunger, “Industrial Organic Pigments” 2^(nd) edition, VCH, 1997,p. 485):

Commercially available acenaphthalene may be successively treated inseparate synthetic steps with malononitrile in the presence of aluminumchloride, sodium perchlorate and hydrochloric acid and finally sodiumhypochlorite and potassium permanganate. The introduction of a R_(n)group(s) at any point in the synthesis or by starting the syntheticprocess from a R_(n) substituted acenaphthalene would yield asubstituted naphthalene tetracarboxylic acid. The use of such asubstituted naphthalene tetracarboxylic acid for the synthesis ofnaphthalene tetrcarboxylic acid diimide dimers as described in thisdevelopment would yield compounds substituted in the R₄, R₅, R₆, R₇, R₈,R₉, R₁₀ and R₁₁ positions of the general structure illustrated inFormula I.

It should also be apparent that for certain choices and combinations ofR₄, R₅, R₆, R₇, R₈, R₉, R₁₀ and R₁₁ the synthetic procedure describedherein may yield structural isomers. For example, if2-chloro-1,4,5,8-naphthalene tetracarboxylic acid was used as a startingmaterial the chloro substituent will end up statistically distributed atthe R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ and R₁₁ positions.

Compounds of the Formula I are generally prepared by a polycondensationreaction of the dihydroxy naphthalene tetracarboxylic diimide dimercomponent with an appropriate compound to yield the desired polymer.FIGS. 3-5 depict illustrative synthesis routes to prepare polycarbonatepolymers. For example FIG. 3 illustrates schematically a method for theformation of a polycarbonate by reaction of a dihydroxyl compoundscontaining a general sub group R13 which would comprise a naphthalenetetracarboxylic acid dimer moiety, with phosgene. Such reactions areusually carried out using a two-phase reaction medium of water (usuallycontaining a hydroxide base, such as sodium hydroxide but usuallypotassium hydroxide) and organic phase. An aqueous phase should bechosen in such a way as to prevent the hydrolysis of the naphthalenetetracarboxylic acid dimer moiety which is a known side reaction andwould not yield the desired polymer. An organic phase should be chosenin such a way as to have the organic phase immiscible with water and soas to provide suitable solubility for the polymer produced and or themonomers if the monomers used in the process are not soluble in aqueoushydroxide base. Phosgene can either be introduced into the reaction as agas, perhaps under pressure, or as a solution in a suitable organicsolvent such as toluene. In this illustration only a homopolymer of thedihydroxyl compound containing a general sub group R13 which wouldcomprise a naphthalene tetracarboxylic acid dimer moiety would beproduced but it would be obvious to those skilled in the art that thepresence of another or several other dihydroxyl compounds in thereaction medium would result in copolymers or higher copolymersrespectively. In another example illustrated in FIG. 4 a polycarbonateis formed in a similar manner as above except in place of phosgene abischloroformate compound (which is made by the treatment of adihydroxyl compound with excess phosgene) is used. Reaction of abischloroformate under similar conditions as those outlined above forthe use of phosgene results in formation of a polycarbonate. If thebischloroformate used in this process is not a derivative of the samedihydroxyl compounds used then the resulting polycarbonate is aperfectly alternating polymer. It would be obvious to those skilled inthe art that the presence of another or several other dihydroxylcompounds or another or several other bischloroformate compounds in thereaction medium would result in copolymers or higher copolymersrespectively. In another example illustrated in FIG. 5 a polycarbonateis formed by reaction of a dihydroxyl compound containing a general subgroup R13 which would comprise a naphthalene tetracarboxylic acid dimermoiety with diphenylcarbonate in a process which could be referred to asa transesterification or transcarbonylation reaction. Conditions usedduring such a process usually are but not limited to high reactiontemperatures, Lewis acid catalyst and a mean for vacuum distillation ofthe produced phenol byproduct. In this illustration only a homopolymerof the dihydroxyl compound containing a general sub group R13 whichwould comprise a naphthalene tetracarboxylic acid dimer moiety would beproduced but it would be obvious to those skilled in the art that thepresence of another or several other dihydroxyl compounds in thereaction medium would result in copolymers or higher copolymersrespectively. These examples are meant as illustrative examples andthose skilled in the art will recognize they may not represent acomplete list of the synthetic methods available for the synthesis ofpolycarbonates.

FIG. 6 depicts an illustrative synthesis route to prepare polyesters andpolyesters of the present disclosure containing a naphthalenetetracarboxylic diimide dimer component. For example FIG. 6 illustratesschematically a method for the formation of a polyester by reaction of adihydroxyl compounds containing a general sub group R15 which would ormay comprise a naphthalene tetracarboxylic acid dimer moiety, with adiacid chloride compound which could optionally also have a general subgroup R14 which would or may comprise a naphthalene tetracarboxylic aciddimer moiety. Such reactions are usually carried out using a two-phasereaction medium of water (usually containing a hydroxide base, such assodium hydroxide but usually potassium hydroxide) and organic phase. Anaqueous phase should be chosen in such a way as to prevent thehydrolysis of the naphthalene tetracarboxylic acid dimer moiety which isa known side reaction and would not yield the desired polymer andhydrolysis of the diacid chloride which is a known side reaction. Anorganic phase should be chosen in such a way as to have the organicphase immiscible with water and so as to provide suitable solubility forthe polymer produced and or the monomers. The diacid chloride could beadded as a solution in a suitable organic solvent such as toluene. Inthis illustration only a homopolymer of the dihydroxyl compound or thediacid chloride containing a general sub group R14 or R15 respectivelywhich would or may comprise a naphthalene tetracarboxylic acid dimermoiety would be produced but it would be obvious to those skilled in theart that the presence of another or several other dihydroxyl compoundsor diacid chloride compounds in the reaction medium would result incopolymers or higher copolymers respectively. In another example apolyester can be formed by reaction of a dihydroxyl compound containinga general sub group R15 which would or may comprise a naphthalenetetracarboxylic acid dimer moiety with diester compound in a processwhich could be referred to as a transesterification. Conditions usedduring such a process usually are but not limited to high reactiontemperatures, Lewis acid catalyst and a mean for vacuum distillation ofthe produced alcohol byproduct. In this illustration only a homopolymerof the dihydroxyl compound or the diester containing a general sub groupR14 or R15 respectively which would or may comprise a naphthalenetetracarboxylic acid dimer moiety would be produced but it would beobvious to those skilled in the art that the presence of another orseveral other dihydroxyl compounds or diester compounds in the reactionmedium would result in copolymers or higher copolymers respectively.These examples are meant as illustrative examples and those skilled inthe art will recognize they may not represent a complete list of thesynthetic methods available for the synthesis of polycarbonates.

FIG. 7 depicts an illustrative synthesis route to prepare polyarylethersand polyarylethers of the present disclosure containing a naphthalenetetracarboxylic diimide dimer component. For example FIG. 7 illustratesschematically a method for the formation of a polyarylene ether byreaction of a dihydroxyl compound containing a general sub group R18which would or may comprise a naphthalene tetracarboxylic acid dimermoiety, with a dihalo compound (where X represents a halide moiety)which is activated by an electron withdrawing group (denoted as Z) whichcould optionally also have a general sub group R19 which would or maycomprise a naphthalene tetracarboxylic acid dimer moiety Such reactionsare usually carried out in the presence of a base such as a carbonatebase which could be sodium carbonate, potassium carbonate, robidiumcarbonate or cesium carbonate. Such reactions are usually carried out inthe presence of a mixture of solvents one (such as for example toluene)to provide azeotropic removal of the water produce and one (such as apolar aprotic solvent like N,N-dimethylformamide (DMF),N,N-dimethylacetamide (DMAc), sulfolane or N-methylpyrrolidinone (NMP))to solubilize both the monomers and polymer produced. Reactionconditions should be chosen in such a way as to produce the desiredpolymer without chemically damaging the naphthalene tetracarboxylic aciddimer moiety. The example is meant as illustrative example and thoseskilled in the art will recognize it may not represent the onlysynthetic method available for the synthesis of polyarylene ethers.

The polymeric materials may also be NTDI containing polymers of theFormula IX:

In embodiments, R₁₂ is independently selected from the group consistingof a hetero atom containing group or a hydrocarbon group that isoptionally substituted at least once with a hetero atom moiety; Inembodiments, R₁₆ is selected from

andwherein R₂₀ may be independently selected from the group consisting of ahetero atom containing group or a hydrocarbon group that is optionallysubstituted at least once with a hetero atom moiety; The R₁₂—R₁₆—R₁₂portion of the polymer of Formula IX is also considered and referred toherein as a binder or resin component of the polymer comprising an NTDIdimer.

FIG. 8 depicts an illustrative synthesis route to prepare naphthalenetetracarboxylic diimide dimer polymides of Formula IX. As shown in FIG.8, a polyimide may be made by polycondensation of a compound of type 2,which may be formed as shown in FIG. 2, and a desired diamino compound.Suitable diamino compounds include compounds of the formula:H₂N—R₁₂—R₁₆—R₁₂—NH₂wherein R₁₂ may be independently selected from the group consisting of ahetero atom containing group or a hydrocarbon group that is optionallysubstituted at least once with a hetero atom moiety; and R₁₆ is selectedfrom:

andwherein R₂₀ may be independently selected from the group consisting of ahetero atom containing group and a hydrocarbon group that is optionallysubstituted at least once with a hetero atom moiety. The R₁₂—R₁₆—R₁₂portion of the polymer of Formula IX is also considered and referred toherein as a binder or resin component of the polymer comprising an NTDIdimer. The reaction is generally carried out in a solution of thecomponents, i.e., a solution of compound 2 and the diamino compound, ina polar aprotic solvent such as DMAC, NMP, DMF, and the like or aphenolic solvent such as m-cresol and the like. The reaction isgenerally carried out at temperatures greater than about 200° C. and mayrequire the presence of a catalyst which is typically isoquinoline orthe like and present in quantities of no more than 10 mole percent.

The NTDI dimer component is present in an amount of about 1 to about 85percent by weight of the polymer, while the binder or resin component ispresent in an amount of about 99 to about 15 percent by weight of thepolymer.

In embodiments, the NTDI dimmer component comprises about 20 to about 50percent by weight of the polymer, and the binder or resin componentcomprises about 80 to about 50 percent by weight of the polymer.

Polymeric materials comprising NTDI dimers, such as, for example,compounds of Formulas I and IX are suitable for use in an active layeror an electrophotographic element in an imaging member. Reference tocompounds of Formula I also includes those polymers of Formulas VI, VII,and VIII. The compounds of Formulas I and IX exhibit dual functionalitywith respect to their use in an imaging member. Specifically, thecompounds of Formulas I and IX are capable of function as a binder andan electron-transporting material. The dual functionality stems from thefact that the compounds are polymeric materials such as, for example,polycarbonates, polyesters, polyarylethers, and polyimides, that includean electron-transporting moiety in the naphthalene tetracarboxylicdiimide dimer component. The compounds of Formulas I and IX are suitablefor use in both multi-layer and single layer photoreceptors.

The photoconductor elements of the disclosure can have any knownconfiguration. The photoconductor elements can have one active layercomprising both a charge generation material and an electron-transportagent of Formula I or Formula IX, or they can be multiactive elements.

In embodiments, the photoconductive elements include a single activelayer. The single active layer comprises a charge generating material, ahole transporting material, and a dual functionalbinder/electron-transporting material of Formula I (including materialsof Formula VI, VII, and VIII), Formula IX or combinations thereof. Inembodiments, the charge generation material is present in an amount offrom about 5 to about 35 percent by weight, the hole transportingmaterial is present in an amount of from about 30 to about 65 percent byweight, and the dual functional binder/electron-transporting material,i.e., the polymer containing the NTDI dimer, is present in an amount offrom about 65 to about 10 weight percent of the single active layercomposition.

Any material suitable as a charge generating material may be used in asingle active layer photoconductive element. Non-limiting examples ofsuitable charge generating materials are described herein. Any materialsuitable as a hole-transporting material may be used in a single activelayer photoconductor element according to the present disclosure.Non-limiting examples of suitable hole-transporting materials or agentsare described herein.

Further, additional electron-transporting materials may be added to thesingle active layer photoconductor element of the disclosure.Non-limiting examples of suitable electron-transport materials aredescribed herein. When additional electron-transporting materials areemployed, the additional electron-transporting material is present in anamount of from about 5 to about 45 percent by weight.

A single active layer of the present disclosure is generally formed bypreparing a particle dispersion with the hole transporting material andoptionally the additional electron-transporting material(s) present in asolid state solution within the polymer materials comprising anaphthalene tetracarboxylic diimide dimer, i.e., the materials ofFormula I (including materials of Formula VI, VII, and VIII) and/orFormula IX. The dispersion may be formed into a single layerphotoreceptor by any suitable method.

In other embodiments, the photoconductive element is a multiactiveelement. The multiactive elements have at least one charge generationlayer having at least one charge generation material and one chargetransport layer having at least one charge transport agent of Formula Ior Formula IX. In addition to charge generation layers and chargetransport layers, the photoconductor elements of this disclosure mayinclude electrically conductive layers and optional additional layers,such as subbing layers, adhesive layers, abrasion resistant layers, andelectronic charge barrier layers which are all well known in the art.

In embodiments, the photoconductor elements of this disclosure havedimensional stability. This can be accomplished by using an electricallyconductive layer that is itself dimensionally stable, or by forming theelement on a dimensionally stable conductive substrate. A dimensionallystable electrically conductive layer or the combination of anelectrically conductive layer and a dimensionally stable substrate willbe referred to as an electrically conductive support. A dimensionallystable substrate may be thermally stable and may be electricallyinsulating. Conventional dimensionally stable substrates such as filmsand sheets of polymeric materials may be used. Examples of polymers usedin films include cellulose acetate, polycarbonates, polyesters, such aspoly(ethylene terephthalate) and poly(ethylene naphthalate), andpolyimides. Typical film substrates have a thickness in the range ofabout 100 to 200 microns, although thicker and thinner layers can beemployed.

The charge transport layer having at least one polymer comprising anaphthalene tetracarboxylic diimide dimer such as a polymer of, forexample, Formula I or Formula IX can be the top layer of thephotoconductor element through which the light or activating energypasses to the charge generation layer, because the compounds of FormulaI and Formula IX are substantially transparent to visible and nearinfrared region light. There will be little or no loss in incident lightas such light passes through a charge transport layer of an imaginglayer in accordance with the disclosure. When the charge transport layeris the top layer, it provides the additional benefit of protecting thecharge generation layer from abrasion caused when paper, cleaningbrushes, or the like, contact the photoconductor element. Thesephotoconductor elements are particularly useful as positively-chargedphotoconductor elements.

Photoconductor elements that include a compound of, for example, FormulaI or Formula IX as the electron-transport agent display photosensitivityin the spectral range of for example about 400 to about 900 nm. Theexact photosensitivity achieved in any given photoconductor element isdependent upon the choice of charge generation material(s), and theconfiguration of layer(s) in the photoconductor element. The term“photosensitivity” as used herein means the capacity of a photoconductorelement to decrease in surface potential upon exposure to actinicradiation. For purposes of the present disclosure, photosensitivity isconveniently measured by corona charging the element to a certainpotential, exposing the charged element to a monochromatic light andmeasuring the decrease of the surface potential. The amount of lightnecessary to discharge the element to a certain potential is defined asthe “exposure requirement” for that potential. The exposure requirementto discharge the photoconductor element to half of its initial value isdenoted E_(0.5).

The photoconductor elements can employ various electrically conductivelayers. For example, the conductive layer can be a metal foil which islaminated to the substrate. Suitable metal foils include those comprisedof aluminum, zinc, copper, and the like. Alternatively, vacuum depositedmetal layers upon a substrate are suitable. Examples of suitable vapordeposited metal include, but are not limited to vapor deposited silver,nickel, gold, aluminum, chromium, and metal alloys. The thickness of avapor deposited metal layer can be in the range of about 20 to about 500angstroms. Conductive layers can also comprise a particulate ordissolved organic or inorganic conductor or semiconductor distributed ina binder resin. For example, a conductive layer can comprisecompositions of protective inorganic oxide and about 30 to about 70weight percent of conductive metal particles, such as a vapor depositedconductive cermet layer as described in U.S. Pat. No. 3,880,657. Alsosee in this connection the teachings of U.S. Pat. No. 3,245,833 relatingto conductive layers employed with barrier layers. Organic conductivelayers can be employed, such as those comprised of a sodium salt of acarboxyester lactone of maleic anhydride in a vinyl acetate polymer, astaught, for example, in U.S. Pat. Nos. 3,007,901 and 3,262,807. Thesubstrate and the conductive layer can also be formulated as aconsolidated layer which can be a metal plate or drum. For example,suitable plates or drums can be formed of metals such as aluminum,copper, zinc, brass and steel.

In the photoconductor elements of the disclosure, the conductive layeris optionally overcoated by a barrier adhesive or subbing layer. Thebarrier layer typically has a dry thickness in the range of about 0.01to about 5 microns. Typical subbing layers are solvent soluble,film-forming polymers, such as, for example, cellulose nitrate, nylon,polyesters, copolymers of poly(vinyl pyrrolidone) and vinylacetate, andvarious vinylidene chloride-containing polymers. Preferred subbinglayers are comprised of nylon, and polyacrylic and methacrylic esters.The barrier layer coating composition can also contain minor amounts ofvarious optional additives, such as surfactants, levelers, plasticizers,and the like.

Any convenient method may be used for the application of a subbinglayer. In embodiments, the subbing layer is formed by dissolving thepolymer in a solvent, and then coating the solution over the conductivelayer.

In embodiments, the solvents are volatile, that is evaporable, attemperatures below about 150° C. Examples of suitable solvents includepetroleum ethers; aromatic hydrocarbons, such as benzene, toluene,xylene, and mesitylene; ketones, such as acetone, and 2-butanone;ethers, such as tetrahydrofuran and diethyl ether; alkanols, such asisopropyl alcohol; and halogenated aliphatic hydrocarbons, such asmethylene chloride, chloroform, and ethylene chloride. Coating solventsinclude for example chlorinated aliphatic hydrocarbons. A nylon subbinglayer may be coated from an alcohol. Mixtures of different solvents orliquids can also be employed.

The barrier layer coating composition is applied by using a techniquesuch as knife coating, spray coating, spin coating, extrusion hoppercoating, curtain coating, or the like. After application, the coatingcomposition is conveniently air dried.

In addition to organic polymers, inorganic materials can be utilized forthe formation of barrier layers. Silicon dioxide, for example, can beapplied to a conductive support by vacuum deposition.

The charge generation layer is applied over the conductive layer, orover the barrier layer, if a barrier layer is employed.

The charge generating (or generation) layer is conveniently comprised ofat least one conventional charge generation material that is typicallydispersed in a polymeric binder. The layer can have a thickness thatvaries over a wide range, typical layer thicknesses being in the rangeof about 0.05 to about 5 microns. As those skilled in the art willappreciate, as layer thickness increases, a greater proportion ofincident radiation is absorbed by a layer, but the likelihood increasesof trapping a charge carrier which then does not contribute to imageformation. Thus, an optimum thickness of a layer can constitute abalance between these competing influences.

Charge generation materials comprise materials that are capable ofgenerating electron/hole pairs upon exposure to actinic radiation in thepresence of an electric field and transferring the electrons to anelectron-transport agent. The charge generation material is present in apolymeric binder or is present as a separate solid phase. The process bywhich electron/hole pairs are generated may require the presence of anelectron-transport agent. Suitable charge generation materials may be,in embodiments, substantially incapable of generating and/ortransferring electrons/hole pairs to an electron-transport agent in theabsence of actinic radiation.

A wide variety of materials known in the art as charge generationmaterials can be employed including inorganic and organic compounds.Suitable inorganic compounds include, for example, zinc oxide, leadoxide, and selenium. Suitable organic materials include variousparticulate organic pigment materials, such as phthalocyanine pigments,and a wide variety of soluble organic-compounds includingmetallo-organic and polymeric organic charge generation materials. Apartial listing of representative materials may be found, for example,in Research Disclosure, Vol. 109, May, 1973, page 61, in an articleentitled “Electrophotographic Elements, Materials and Processes”, atparagraph IV(A) thereof. This partial listing of well-known chargegeneration materials is hereby incorporated by reference.

Examples of suitable organic charge generation materials includephthalocyanine pigments such as a bromoindium phthalocyanine pigmentdescribed in U.S. Pat. Nos. 4,666,802 and 4,727,139, or atitanylphthalocyanine pigment such as a titanyl tetrafluoropthalocyaninedescribed in U.S. Pat. No. 4,701,396; various pyrylium dye salts, suchas pyrylium, bispyrylium, thiapyrylium, and selenapyrylium dye salts, asdisclosed, for example, in U.S. Pat. No. 3,250,615; fluorenes, such as7,12-dioxo-13-dibenzo(a,h)fluorene, and the like; aromatic nitrocompounds of the kind disclosed in U.S. Pat. No. 2,610,120; anthronessuch as those disclosed in U.S. Pat. No. 2,670,284; quinones such asthose disclosed in U.S. Pat. No. 2,670,286; thiazoles, such as thosedisclosed in U.S. Pat. No. 3,732,301; various dyes such as cyanine(including carbocyanine), merocyanine, triarylmethane, thiazine, azine,oxazine, xanthene, phthalein, acridine, azo, anthraquinone dyes, and thelike, and mixtures thereof.

The charge generation material, or a mixture of charge generationmaterials, is usually applied from a solution or dispersion in a coatingcomposition to form a charge generating layer in an element over abarrier layer of the type described herein. Also typically present asdissolved solids in a charge generation layer coating composition are abinder polymer and optional additives, such as surfactants, levelers,plasticizers, sensitizers, and the like. The solids comprising a chargegeneration layer on a 100 weight percent total basis typically comprise1 to about 70 weight percent of charge-generation material, 0 to about99 weight percent of polymeric binder, and 0 to about 50 weight percentof total additives. In embodiments, the coating composition containsfrom about 6 to about 15 weight percent of solids, the balance beingsolvent. Suitable solvents are those identified above in relation to thebarrier layer. In embodiments, additives for a composition to be coatedto form a charge generation layer are charge transport agents andsurfactants.

Any hydrophobic organic polymer known to the photoconductor element artas a binder can be used for the polymeric binder in the chargegenerating layer. These polymers are film forming and are preferablyorganic solvent soluble, and, in solid form, display high dielectricstrength and electrical insulating properties. Suitable polymersinclude, for example, styrene-butadiene copolymers; polyvinyltoluene-styrene copolymers; silicone resins, styrene alkyd resins,silicone-alkyd resins; soya-alkyd resins; poly(vinyl chloride);poly(vinylidene chloride); vinylidene chloride-acrylonitrile copolymers;poly(vinyl acetate); vinyl acetate-vinyl chloride copolymers; poly(vinylacetate); vinyl acetate-vinyl chloride copolymers; poly(vinyl acetals),such as poly(vinyl butyral); polyacrylic and methacrylic esters, such aspoly(methyl methacrylate), poly(n-butyl methacrylate), poly(isobutylmethacrylate), etc.; polystyrene, nitrated polystyrene;polymethylstyrene; isobutylene polymers; polyesters, such aspoly[4,4′-(2-norbornylene)bisphenylene azelate-co-terephthalate(60/40)],andpoly[ethylene-co-alkylene-bis(alkylene-oxyaryl)-phenylenedicarboxylate];phenolformaldehyde resins; ketone resins; polyamides; polycarbonates;polythiocarbonates;poly[ethylene-co-isopropylidene-2,2-bis(ethyleneoxyphenylene)terephthalate];copolymers of vinyl haloarylates and vinyl acetate, such aspoly(vinyl-m-bromobenzoate-co-vinyl acetate); chlorinated polyolefinssuch as chlorinated polyethylene; and the like. In embodiments, polymersmay be either polyesters or polycarbonates.

One or more charge transport agents can be added to a charge generationlayer coating composition, such as1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, as taught in U.S. Pat. No.4,127,412, tri-p-tolylamine, and the like or, electron-transport agents,such as compounds of Formula I or Formula IX, or any otherelectron-transport agents known to the art. Coating aids, such aslevelers, surfactants, cross linking agents, colorants, plasticizers,and the like, can also be added. The quantity of each of the respectiveadditives present in a coating composition can vary, depending uponresults desired and user preferences.

A charge generating layer composition is applied by coating thecomposition over the barrier layer using a technique such as abovedescribed for coating a barrier layer composition. After coating, thecharge generating layer composition is usually air dried.

Instead of a charge generation material being dispersed in a polymericbinder, a charge generation layer can, in some cases, depending upon thecharge generation material involved, be comprised substantially entirelyof only such a material. For example, a perylene dicarboximide pigmentof the Formula in column 11, line 45, of U.S. Pat. No. 5,468,583,wherein R is an aryl or arylalkylenyl group, can be applied over anelectrically conductive layer under vacuum by sublimination, such asunder subatmospheric pressures of about 10⁻² to about 10⁻⁵ mm Hg attemperatures in the range of about 200° C. to about 400° C.

An illustrative charge generation material comprisestitanylphthalocyanine or titanyl tetrafluorophthalocyanine pigmentdescribed in U.S. Pat. No. 4,701,396, the disclosure of which isincorporated herein by reference. An illustrative binder in the chargegenerating layer is poly [4,4′-(2-norbornylene)bisphenyleneazelate-co-terephthalate(60/40)].

The charge transport layer is applied over the charge generation layer.When the charge transport layer contains at least one compound ofFormula I and Formula IX, an electron-transporting charge transportlayer is produced.

A charge transport layer, if desired, can contain, in addition to atleast one compound of Formula I and Formula IX, at least one additionalelectron-transport agent of a type known to the art. Suitableelectron-transport agents include, but are not limited to,2,4,7-trinitro-9-fluorenone, substituted 4-dicyanomethylene-4H-thiopyran1,1-dioxides, and substituted anthraquinone biscyanoimines.

The charge transport layer comprises at least one of the compounds ofFormula I (including the compounds of Formula VI, VII, and VIII) and/orFormula IX. As previously described herein, the compounds of Formula Iand Formula IX are capable of functioning as both a binder and anelectron-transporting material. Thus, in embodiments, the chargetransport layer may include 100 weight percent of a compound of FormulaI or Formula IX or a combination of compounds of Formula I and FormulaIX. In other embodiments, the charge transport layer may include one ormore additional electron-transporting materials. In embodiments, thecharge transport layer may comprise from about 30 to about 90 percent byweight of a compound or material of Formula I, or Formula IX, orcombinations thereof, and from about 10 to about 70 percent by weight ofan electron-transporting material (other than the compounds of FormulasI and IX).

The thickness of the charge transport material is not limited, otherthan by size constraints. Typically, a charge transport layer has athickness in the range of about 10 to about 25 microns, although thickerand thinner layers can be employed.

A charge transport layer can be produced in a bipolar form, if desired,by additionally incorporating into the layer at least one hole transportagent. Such an agent preferentially accepts and transports positivecharges (holes). If employed, the quantity of hole transport agent(s)present in a charge transport layer on a total layer weight basis may bein the range of about 10 to about 50 weight percent, although larger andsmaller quantities can be employed.

Examples of suitable organic hole transport agents known to the priorart include, but are not limited to carbazoles, arylamines,polyarylalkanes, strong lewis bases, and hydrazones.

Suitable carbazoles include, but are not limited too, carbazole, N-ethylcarbazole, N-isopropyl carbazole, N-phenyl carbazole, halogenatedcarbazoles, various polymeric carbazole materials such as poly(vinylcarbazole), halogenated poly(vinyl carbazole), and the like.

Suitable arylamines include, but are not limited to monoarylamines,diarylamines, triarylamines and polymeric arylamines. Specific arylamineorganic photoconductors include the nonpolymeric triphenylaminesillustrated in U.S. Pat. No. 3,180,730; the polymeric triarylaminesdescribed in U.S. Pat. No. 3,240,597; the triarylamines having at leastone of the aryl radicals substituted by either a vinyl radical or avinylene radical having at least one active hydrogen-containing group,as described in U.S. Pat. No. 3,567,450; the triarylamines in which atleast one of the aryl radicals is substituted by an activehydrogen-containing group, as described by U.S. Pat. No. 3,658,520; andtritolylamine.

Suitable polyarylalkanes, include, but are not limited, to those of thetype described in U.S. Pat. Nos. 3,274,000; 3,542,547; 3,625,402; and4,127,412.

Examples of suitable strong Lewis bases, such as aromatic compounds,including aromatically unsaturated heterocyclic compounds free fromstrong electron-withdrawing groups. Examples include tetraphenylpyrene,1-methylpyrene, perylene, chrysene, anthracene, tetraphene,2-phenylnaphthalene, azapyrene, fluorene, fluorenone, 1-ethylpyrene,acetyl pyrene, 2,3-benzochrysene, 3,4-benzopyrene, 1,4-bromopyrene,phenylindole, polyvinyl carbazole, polyvinyl pyrene, polyvinyltetracene,polyvinyl perylene and polyvinyl tetraphene.

Suitable hydrazones include, but are not limited to thedialkyl-substituted aminobenzaldehyde-(diphenylhydrazones) of U.S. Pat.No. 4,150,987; alkylhydrazones and arylhydrazones as described in U.S.Pat. Nos. 4,554,231; 4,487,824; 4,481,271; 4,456,671; 4,446,217; and4,423,129, which are illustrative of the hydrazone hole transportagents.

Other useful hole transport agents are described in Research Disclosure,Vol. 109, May, 1973, pages 61-67 paragraph IV(A)(2) through (13).

One or more other electron-transporting agents may be used with thepresent multi-functional or hybrid polymers comprising naphthalenetetracarboxylic diimide dimers in photoconductor elements and otherelectronic devices. Examples of such other electron-transporting agentsinclude: a) carboxylfluorenone malonitrile (CFM) derivatives representedby the general structure:

wherein each R is independently selected from the group consisting ofhydrogen, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40carbon atoms, phenyl, substituted phenyl, higher aromatic such asnaphthalene and anthracene, alkylphenyl having 6 to 40 carbon atoms,alkoxyphenyl having 6 to 40 carbon atoms, aryl having 6 to 30 carbonatoms, substituted aryl having 6 to 30 carbon atoms and halogen; b) anitrated fluoreneone derivative represented by the general structure:

wherein each R is independently selected from the group consisting ofhydrogen, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40carbon atoms, phenyl, substituted phenyl, higher aromatic such asnaphthalene and anthracene, alkylphenyl having 6 to 40 carbon atoms,alkoxyphenyl having 6 to 40 carbon atoms, aryl having 6 to 30 carbonatoms, substituted aryl having 6 to 30 carbon atoms and halogen, and atleast 2 R groups are chosen to be nitro groups; c) a1,1′-dioxo-2-(aryl)-6-phenyl-4-(dicyanomethylidene)thiopyran derivativerepresented by the general structure:

wherein each R is independently selected from the group consisting ofhydrogen, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40carbon atoms, phenyl, substituted phenyl, higher aromatic such asnaphthalene and anthracene, alkylphenyl having 6 to 40 carbon atoms,alkoxyphenyl having 6 to 40 carbon atoms, aryl having 6 to 30 carbonatoms, substituted aryl having 6 to 30 carbon atoms and halogen; d) Acarboxybenzylnaphthaquinone derivative represented by the followinggeneral structure:

wherein each R is independently selected from the group consisting ofhydrogen, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40carbon atoms, phenyl, substituted phenyl, higher aromatic such asnaphthalene and anthracene, alkylphenyl having 6 to 40 carbon atoms,alkoxyphenyl having 6 to 40 carbon atoms, aryl having 6 to 30 carbonatoms, substituted aryl having 6 to 30 carbon atoms and halogen; e) adiphenoquinone represented by the following general structure:

and mixtures thereof, wherein each R is independently selected from thegroup consisting of hydrogen, alkyl having 1 to 40 carbon atoms, alkoxyhaving 1 to 40 carbon atoms, phenyl, substituted phenyl, higher aromaticsuch as naphthalene and anthracene, alkylphenyl having 6 to 40 carbonatoms, alkoxyphenyl having 6 to 40 carbon atoms, aryl having 6 to 30carbon atoms, substituted aryl having 6 to 30 carbon atoms and halogen.

Additionally, another suitable electron-transporting agent includes anaphthalene tetracarboxylic diimide dimer as described in U.S.application Ser. No. 10/197,933, published as U.S. Patent ApplicationPublication No. 2004/0013959.

In addition to an electron-transport agent of Formula I or Formula IX,and optionally additional charge transport agent(s) and a binderpolymer, the charge transport layers in the photoconductor elements ofthis disclosure may contain various optional additives, such assurfactants, levelers, plasticizers, and the like. On a 100 weightpercent total solids basis, a charge transport layer can contain forexample up to about 15 weight percent of such additives, although it maycontain less than about 1 weight percent of such additives.

In embodiments, the charge transport layer solid components areconveniently preliminarily dissolved in a solvent to produce a chargetransport layer composition containing for example about 8 to about 20weight percent solids with the balance up to 100 weight percent beingthe solvent. The solvents used can be those hereinabove described.

Coating of the charge transport layer composition over the chargegeneration layer can be accomplished using a solution coating techniquesuch as knife coating, spray coating, spin coating, extrusion hoppercoating, curtain coating, and the like. After coating, the chargetransport layer composition is usually air dried.

A charge transport layer can be formed of two or more successive layerseach of which has the same or different total solids composition. Insuch event at least one charge transport sublayer contains at least onecompound of Formula I or Formula IX.

Photoconductor elements of this disclosure may display dark decay valuesof for example no more than about 20 V/sec, or no more than about 5V/sec. The term “dark decay” as used herein means the loss of electriccharge and consequently, electrostatic surface potential from a chargedphotoconductor element in the absence of activating radiation.

For present purposes of measuring dark decay, a single-active-layerphotoconductive element or a multilayered photoconductor element ischarged by use of a corona discharge device to a surface potential inthe range of about +300 to about +600 volts. Thereafter, the rate ofcharge dissipation and decrease of surface potential in volts per secondis measured. The element is preliminarily dark adapted and maintained inthe dark without activating radiation during the evaluation usingambient conditions of temperature and pressure.

Suitable photoconductor elements display reusability, that is, theability to undergo repeated cycles of charging and discharging withoutsubstantial alteration of their electrical properties.

Those skilled in the art will appreciate that other variations in thestructure of photoconductor elements incorporating a compound of FormulaI or Formula IX are possible and practical. For example, variousdifferent layer arrangements can be employed. Thus, a transport layercan be positioned between two charge generation layers which can havethe same or different respective compositions and layer thicknesses.Also, a charge generation layer can be positioned between twocharge-transport layers only one of which may contain a compound ofFormula I or Formula IX.

The exemplary embodiment has been described with reference to thevarious specific embodiments. Obviously, modifications and alterationswill occur to others upon reading and understanding the precedingdetailed description. It is intended that the exemplary embodiment beconstrued as including all such modifications and alterations insofar asthey come within the scope of the appended claims or the equivalentsthereof.

1. A photoimaging member comprising: a substrate; a charge generatinglayer; and a charge transport layer, wherein said charge transport layercomprises a polymer composition comprising a polymer selected from thegroup consisting of a polymer of Formula I:

and a polymer of Formula IX

wherein A is selected from

R₁ is independently selected from the group consisting of a hetero atomcontaining group, a hydrocarbon group, and a hydrocarbon groupsubstituted at least once with a hetero atom moiety; R₂ and R₃ areindependently selected from the group consisting of a hydrocarbon groupor a substituted hydrocarbon group; R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁are independently selected from the group consisting of a nitrogencontaining group, a sulfur containing group, a hydroxyl group, a siliconcontaining group, hydrogen, a halogen, a hetero atom containing group, ahydrocarbon group, and a hydrocarbon group substituted at least oncewith a hetero atom moiety; R₁₂ is independently selected from the groupconsisting of a nitrogen containing group, a sulfur containing group, ahydroxyl group, a silicon containing group, hydrogen, a halogen, ahetero atom containing group, a hydrocarbon group and a substitutedhydrocarbon group; R₁₃ is selected from the group consisting of

R₁₄ is selected from the group consisting of a hydrocarbon group and asubstituted hydrocarbon; R₁₅ is selected from the group consisting of

wherein Z is an electron withdrawing group; R₁₆ is selected from thegroup consisting of

and wherein R₁₇ is independently selected from the group consisting of anitrogen containing group, a sulfur containing group, a hydroxyl group,a silicon containing group, hydrogen, a halogen, a hetero atomcontaining group, a hydrocarbon group and a substituted hydrocarbongroup; and n is a fraction between 0 and
 1. 2. The photoimaging memberof claim 1, wherein the polymer is a polycarbonate of Formula VI

and n is a fraction between 0 and
 1. 3. The photoimaging member of claim1, wherein the polymer is a polyester of Formula VII

and n is a fraction between 0 and
 1. 4. The photoimaging member of claim1, wherein the polymer is a polyarylether of Formula VIII

and n is a fraction between 0 and 1.